In recent years, a number of systems and methods have been proposed for occupancy detection within a particular area utilizing radio frequency (RF) based technologies. Examples of such systems include video sensor monitoring systems, radio frequency identification (RFID) systems, global positioning systems (GPS), and wireless communication systems among others. However, many of these systems have several disadvantages. For example, the video sensor monitoring system requires a considerable number of dedicated sensors that are expensive and the system requires a large amount of memory for storing data. The RFID systems rely on occupants carrying an RFID tag/card that can be sensed by the RFID system to monitor the occupants. The GPS system uses orbiting satellites to communicate with the terrestrial transceiver to determine a location of the occupant in the area. However, such systems are generally less effective indoors or in other environments where satellite signals may be blocked, reducing accuracy of detecting the occupant in the area.
Electrically powered artificial lighting has become ubiquitous in modern society. Since the advent of electronic light emitters, such as lighting emitting diodes (LEDs), for general lighting type illumination application, lighting equipment has become increasingly intelligent with incorporation of sensors, programmed controller and network communication capabilities. Automated control, particularly for enterprise installations, may respond to a variety of sensed conditions, such a daylight or ambient light level or occupancy. Commercial grade lighting systems today utilize special purpose sensors and related communications.
There also have been proposals to detect or count the number of occupants in an area based on effects on an RF signal received from a transmitter due to the presence of the occupant(s) in the area. These RF wireless communication systems generally detect an occupant in the area based on change in signal characteristics of a data packet transmitted over the wireless network. However, an inaccurate detection of the occupant in a region or a sub-area in the area can occur when multiple transmitters are transmitting the RF signals from multiple different regions/sub-areas of the area.